Project Eternity - Update #44, Rules of Engagement

Last week, our art director, Rob, showed you our godlike concepts and dazzled you with an in-depth technical breakdown of how we're doing animation rigging on the project. This week, we'll be talking about a different technical subject, but one that's more connected to gameplay: engagement — specifically, melee engagement.
Melee engagement is a solution to two common problems in the Infinity Engine games: melee characters' inability to control an area and ranged characters' ability to "kite" melee characters. In the Infinity Engine games, melee characters could be quite powerful in toe-to-toe combat, but many opponents found ways to foil those characters with little difficulty. Fast characters could easily rush around a slower melee character with impunity and ranged characters could backpedal perpetually out of reach.
If you're familiar with D&D 3E/3.5/4E/Pathfinder's attack of opportunity mechanics, Project Eternity's melee engagement fills a similar role by making melee combatants "sticky". Coming near a melee combatant means being drawn into Engagement with him or her, a state that can be risky to get out of.
Here's how it works: when two opposed combatants come near each other and one of them a) has a melee weapon equipped b) is not moving and c) is not currently at his or her maximum limit of engagement targets (the standard is 1), the other character will be Engaged.
When an opponent is Engaged by an attacker, moving any significant distance away from the attacker will provoke a Disengagement Attack. A Disengagement Attack has an inherent Accuracy bonus, does significantly more damage than a standard attack, and will call a hit reaction animation while momentarily stopping the character's movement.
When it's initiated, a Disengagement Attack automatically breaks Engagement on the target, but if the target is also the attacker's current melee target, the attacker will typically be able to re-establish Engagement before the target can move farther away. In this manner, melee combatants, especially ones that have high Accuracy and damage per hit, have a solid mechanic for keeping enemies close to them — or making the cost of escape extremely expensive.
Of course, there are other ways to end Engagement. If the attacker switches to a non-melee weapon or performs a non-melee-based action, Engagement immediately ends. If the attacker moves away from their Engagement targets, is paralyzed, knocked down, or otherwise prevented from maintaining a threat, Engagement will also immediately end. If the attacker has a limited number of Engagement targets (as most do) and switches his or her attack focus to a different character, Engagement immediately ends.
We believe that Engagement can give AI a clear "decision point" where they can evaluate the threat of their new status and choose the appropriate course of action. For player-controlled characters, it makes melee enemies more potent threats and presents players with tactical challenges to solve.
We want Engagement to be a mechanic that players and enemies can mess with using a variety of class Abilities and general Talents, so we will be experimenting with a variety of elements to that end:

Fighters' Defender mode allows them to engage two additional targets and increases the range at which they engage targets. This gives fighters much greater capability to control the area around them.

The limited-use Escape ability lets rogues break Engagement without provoking a Disengagement Attack. It is generally best used when the rogue's enemy is preoccupied with another target.

Barbarians can use Wild Rush to temporarily ignore the movement stop and hit reactions from Engagement and Disengagement Attacks, respectively — though they can still suffer massive damage while powering through.

The wizards' Grimoire Slam allows them to attack an enemy in melee with their magically-charged grimoires, unleashing a concussive wave of energy on contact. If it hits, the attack knocks the target back, usually far enough to break Engagement in the process.

Additionally, creatures may have their own special abilities related to Engagement and Disengagement Attacks. We hope that the system itself is easy to understand but allows for increasingly complex tactical considerations over the course of the game.